Bifocal-lens grinder.



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B. MAYER.

BrFOCAL LENS GRINDER.

APPLICATION FILED 1AN.6,1913.

1,181,471 Patented Maly 2, 1916.

UNITED sTATEs PATENT oEEicE.

BENJAMIN MAYER, F BALTIMORE, MARYLAND, ASSIGNOR T0 THE BISIGHT COMPANY, OF BALTIMORE, MARYLAND, A CORPORATION OF MARYLAND.

BIrpcaL-LENS GEI'NDER.

Specification of Letters Patent.

Patented May 2, 1916.

Application led January 6, 1913. Serial No. 740,564.

' To all whom it may concern.'

Be it known that I, BENJAMIN MAYER, a citizen of the United States, residing at Baltimore, in the State of Maryland, have invented certain new and useful Improvements in Bifocal-Lens Grinders, of which the following is a speciiication.

his invention relates to lens-grinding machines, and has especial reference to that class of devices designed to grind or polish one-piece bifocal lenses.

The object of my invention is to provide a simple and inexpensive device adapted to grind a glass-blank to a double lens-blank having a circular inner field of the particular curvature required of the near-vision portion of the lenses, and an encircling or outer .field of the curvature required of the distance-vision portion of the lenses, the resulting blank beingv subsequently divided and finished in the usual manner t produce two bifocal lenses.

The invention is illustrated in the accompanying drawings, wherein:

Figure l is a transverse vertical section of the grinding machine; Fig. 2 is a plan o the machine; and Fig. 3 is a plan of the bifoeal side of the lens-blank, after the grinding is completed, ready for division into two uncut lenses.

rlhe apparatus illustrated comprises an emery-paii 1 of the usual type, mounted upon a table or other support A shaft 3, adapted to be rotated by any suitable means, as by a pulley 3', passes through the emerypan 1, and is connected at its upper end with the lower side of a 4, which rotates with it. W'itliin a pocket in the upper face of otherwise secured the glass-blind; 1' which is to he. Irwin/l. At suitable points on the e 'fcd two standards which supa cross-bar G. On this bar are slidably mounted two clamps 7, 7', ol' any suitable form, receiving rod's 8, 8,

but udjusfably, and a horizontally aperiured pro-lion lf3, adapted to receive the ihreaiioil bolts l', in such manner that upon tightening up the bolts, the portion 16 will glass-blank holding-diskl the disk 4r is cemented or be :securely held against the split-sleeves 18 adiustably mounted on the bar 6. The lower ends of the rods 8, 8', enter pockets 9, 9' in .the grinding-disks 10, 10', and hold them in contact with the inner and outer portions, respectively, of the upper surface of the glass-blank 4', in such position as to grind the desired curvatures thereon. The grinding disks are free to rotate, and do rotate, about their own axes, thus bringing the whole surface of the disks into constantly varying contact with the lens surface, thereby avoiding all streaks or striations in the lens surface. The grinding disk 10 is somewhat sm'lfler than the disk 10, and grinds the central smaller near-vision portion, while disk 10 grinds' the larger annular distance-field.

In using my device, the glass-blank 4 is secured in the disk 4;l the rod 8 is adjusted by means of the clamp so that the smaller grinding disk 10 is held nearly upoirsthe center of the blank 4', its eiractrloztion eing determined by the required size of the near-vision portion; and the rod 8' is adjusted by means of the clamp 7 so that the larger grinding-disk 10' is held in contact with the blank outside of hre circular area traversed by the smallerv grinding-disk. As

-cu'rvature 13 of the distance-field, determined by the adjustment of rod 8'. When the grinding is completed, the blank 'is divided along the line A-B, thus producing two bifocal lens-blanks. By the use of this machine, a bifocal lens can be produced having either a definite dividing line or an invisible merger between the two fields of vision. By-covering the faces of the disks 10 and 10' with cloth or like material, the

machine may be used for polishing the lensblank, rouge being supplied.

I claim:

.1 onepiece bifoeal-lens grinding machine, comprising, a revolublc blank-support, a near-vision grinder, :i distance-Held grinder, a cross-bar mounted above said blank-support, rods carried by said cross-bar In testimony whereof I ax my signature and holding said grindersvn Contact respecin presence of two Witnesses. tively Withfthe central and outer portions -of the blanks, said grinders' being free t-o i BENJAMIN MAYER' 5 rotate on their own axes, and means for ad- Witnesses:

justing the positions of said rods and grnd- C. W. FOWLER,

ers to produce the desired curvatures. C. H. POTTER. 

